For the most part,
the design of a space suit is based on the environment in which it will
operate. Space shuttle space suits, for use in Earth orbit, are designed
to operate in avacuum and in microgravity.

Mars space suit A space suit that will be used on the surface of Mars will require a different
design. Astronauts exploring the Martian surface will have to wear space
suits that will protect them from the very thin atmosphere, a lack of oxygen,
and extremely cold temperatures. These space suits must be lightweight
and flexible enough to allow astronauts to work and move about freely,
but durable enough to withstand the rugged and dusty surface. The space
suits that will be needed on Mars are currently in the design and development
stage. The Mars suit will probably weigh about 80 pounds on Earth; on Mars
that would only be about 27 pounds.

Tests are being conducted in
Mars-like terrains here on Earth in Flagstaff, Arizona, to evaluate the
flexibility, mobility, and durability of the suits and the different types
of suit materials and components.

One concern is to provide protection from
the dust carried by Martian winds that will be kicked up by the explorers.
Until samples of the Martian sediment are returned to Earth, we won't know
how abrasive it will be.

These and other properties of the Martian environment
provide interesting and exciting challenges to space suit designers and
builders.Explorers on Mars will need to use a variety
of tools and scientific equipment. To carry these things, they will use
robotic rover assistants.

These robots will not only be "pack mules." They
will also be able to explore, acting as pathfinders and collecting samples
from places that are too far or too dangerous for the crew to explore.
Currently, engineers at NASA’s Johnson Space Center are developing special
tools based on the ones used in the Apollo Program. Hammers, axes, walking
sticks (‘mobility aides’), tongs (‘grabbers’), and hand corers (for soil
samples) are being designed to fit pressured suit gloves. Pressure will
be kept at 3.75 pounds per square inch inside the suit. This pressure is
similar to that of the suits worn by the Apollo astronauts on the Moon
in order to allow for more mobility. Click
here to download a brief about the history of space suit
development (large .pdf file).

Previous trials in the high
desert near Flagstaff have tested the suits and tools in rover-aided expeditions.
The Marsokhod Russian rover was used to test the interaction between extravehicular
activity (EVA) astronauts and teleoperated rovers.

The rover was used as a scout to find interesting
targets and a safe site. Once the target was identified, the astronaut
followed its path. The rover was also used to video document the crewmember’s
activity and as a field assistant. In this scenario, the astronaut led
the expedition by planting flags of different colors corresponding to tasks
he wanted the rover to do; i.e., collect rock or soil samples, take pictures
of the scene, take close ups of objects, or photograph the ground. Hazard
flags were also used to keep the rovers out of trouble. While the rover
was going to the designated sites, the astronaut continued his traverse.
Humans can pinpoint sites of scientific interest much faster than robots
can. Finally, the rover was used as a field technical assistant, carrying
samples and tools for the suited astronaut.

This autumn, a field test will
be done to test four new objectives: the laying of power cables, the deployment
of solar panels, the use of a drilling rig (to dig down to 25 feet), and
making extravehicular activity (EVA) traverses and tool evaluations. A
large driving rover will be used that is similar to the rover astronauts
will drive around the surface of Mars.

The plan is for Mars astronaut backpacks
to be made lighter by allowing them to recharge at the rover instead of
having the astronauts carry 8 hours' worth of power and life support with
them. The six-wheel-drive rover carries tools, air supply, a generator,
and a communications system (audio and video).

Since crews would be working
near the rover, this is a feasible plan. The Johnson Space Center is currently
considering building a small facility that will resemble the Martian terrain
to do testing of suits, tools, rovers, and equipment at the Center in Houston,
Texas. A partial gravity balance simulator
that can simulate 1/3g (Martian gravity forces) here on Earth is also being
tested. When attached to the space suit, astronauts
would feel like they were on Mars.For more information, click on the following
links:Mars
suitsToolsQuestions to think about:

What would be the most difficult part of exploring
the surface of Mars in a space suit?

Which activities would be more dangerous or
difficult?

What types of support would you need?

What tools and equipment could help you explore
very high mountains, steep cliffs or rocky terrain?

Anextremophile(from Latinextremusmeaning "extreme" and Greekphiliā(φιλία) meaning "love") is anorganismthat thrives in physically or geochemicallyextreme conditionsthat are detrimental to mostlife on Earth

Extraterrestrial Life?

NOAA/NASA

No, scientists have not yet found life beyond Earth. This is a methane ice worm that burrows deep into methane ice in the Gulf of Mexico. How do you think studying organisms that live in extreme environments on Earth helps scientists search for life beyond Earth?

Conditions for Life on Earth

Life exists in nearly every environment on Earth. Some environments have conditions so extreme that humans cannot live in them. These places might have extreme temperatures, high salt levels, total darkness, or little water. Even though humans cannot live in these places, other organisms can.

Despite the extreme conditions in which some organisms live, all of Earth’s life-forms need the same basic things to survive: a source of energy, liquid water, and nourishment. Scientists have not yet found life anywhere else in the solar system. But by studying the conditions that support life on Earth, they are learning about conditions that might support life elsewhere. Astrobiologyis the study of the origin, development, distribution, and future of life in the universe.

1.Key Concept CheckWhat do organisms on Earth need to survive?

Energy from the Sun

The Sun is the source of almost all energy on Earth. Sunlight provides light and thermal energy. It also provides energy for plants, which are at the base of most food chains. However, a small percentage of organisms on Earth receive energy from chemicals or from Earth itself, such as the animals shown in Figure 1.

DR KEN MACDONALD/SCIENCE PHOTO LIBRARY

Figure 1A variety of animals live in complete darkness near hot water jets in the ocean floor.

Protection by the Atmosphere

Earth’s moon receives about the same amount of sunlight as Earth. Yet conditions on the Moon are more extreme than they are on Earth. The Moon’s surface temperature can rise to 100°C during the day and drop to −150°C at night. Temperatures are extreme on the Moon because the Moon, unlike Earth, does not have an atmosphere.

Maintains TemperaturesEarth’s atmosphere is like a blanket around Earth. It absorbs sunlight during the day and keeps heat from escaping into space during the night. It maintains Earth’s average surface temperature at a comfortable 14°C.

2.Reading CheckHow is Earth’s atmosphere like a blanket?

Absorbs Harmful RadiationHave you ever had a painful sunburn? Sunburns are caused by the Sun’s ultraviolet light. Even though you cannot see ultraviolet light, you can feel its effects. Too much ultraviolet light can harm you. Fortunately, Earth’s atmosphere absorbs most of the Sun’s ultraviolet light, as well as X-rays and other potentially harmful light from the Sun. The atmosphere also helps protect Earth from highly charged particles that erupt from the Sun in powerful storms.

Burns Up MeteoroidsEarth’s atmosphere also protects Earth’s surface from meteoroids. Millions of meteoroids strike Earth’s atmosphere every day. But almost all of them burn up in the atmosphere before they can hit Earth’s surface.

Liquid Water

Liquid water is necessary for all life on Earth. Water dissolves minerals and transports molecules in cells. Without liquid water, cells could not function and life would not exist. Earth’s atmosphere keeps pressures and temperatures on Earth’s surface within a range where water can exist as a liquid.

Depending on temperature and pressure on Earth, water is solid, liquid, or gas, as shown in Figure 2.At sea level on Earth (1 atm of pressure), water is liquid between 0°C and 100°C. Above 100°C, water boils and becomes water vapor. Below 0°C, it freezes into ice. However, at different altitudes on Earth, such as on the top of a mountain, the boiling and freezing temperatures of water change slightly because the pressure in the atmosphere changes. Without Earth’s atmosphere, pressures on Earth’s surface would be too low for water to be liquid. Water would exist only as water vapor or ice.

3.Key Concept CheckWhat would happen to water on Earth’s surface if Earth had no atmosphere?

Figure 2Water changes from liquid into gas or into solid as temperatures and pressures change.

Visual CheckWhat happens to water when temperatures are high?

Nourishment

Living things are nourished by nutrients they take from the air, water, and land around them. They use the nutrients for energy, growth, and other processes, such as reproduction and cellular repair. All molecules that provide nourishment for life on Earth contain carbon. They are organic molecules. Organicrefers to a class of chemical compounds in living organisms that are based on carbon. Though it is possible that inorganic life could exist elsewhere, astrobiologists are most interested in places beyond Earth where water is liquid and carbon is plentiful.

Common Userelating to food grown without fertilizers, pesticides, or antibiotics

Looking for Life Elsewhere

In 1835, a New York newspaper published articles claiming that herds of bison and furry, winged bat-men had been observed on Earth’s moon. Many people were fooled. Today, people know the Moon is airless, and scientists have yet to find life there. Because liquid water is essential for life on Earth, scientists look for places in our solar system where liquid water might exist or might have existed in the past. In 2009, scientists discovered water on the Moon. Although water might not exist on the surface of a planet or a moon, it might exist beneath the surface.

Mars

Other than Earth, Mars is the planet scientists think is most likely to have liquid water. On the surface of Mars, pressures probably are too low for water to be liquid; water would likely evaporate quickly in the thin, dry atmosphere. Temperatures are also low. They generally range from −87°C to −5°C, though they can reach a high of 20°C during the Martian summer.

Scientists have sent many uncrewed spacecraft to Mars, but none has detected liquid water. However, there is abundant evidence for water vapor and water ice on the Martian surface. And photographs show surface features on Mars that appear to have been carved by moving water. The channels shown in Figure 3look like streambeds. It is possible that water from an underground ocean seeped to the surface and flowed as rivers or floods before evaporating. How much water was in these channels and how long ago it flowed are still unknown.

1.Key Concept CheckWhy do scientists think liquid water once might have existed on Mars?

NASA/JPL/University of Arizona

Figure 3Scientists hypothesize that these Martian channels could be ancient streambeds.

Other Planets

Mercury and Venus are too hot for water to be liquid on or near their surfaces. The four outer planets are too cold. The outer planets also are too gaseous. They have no solid surfaces on which liquid water could form. Though some liquid water might exist deep in the interiors of the outer planets, it is unlikely that the water could support life.

Natural Satellites

Scientists continue to look for further evidence of water on Earth’s moon and on the moons of other planets. Even though temperatures in the outer solar system are extremely cold, scientists have found that as a satellite orbits a massive planet, the planet’s gravity can cause the satellite’s interior to heat. This might provide enough thermal energy to allow liquid water to exist near their icy surfaces.

Several moons in the outer solar system have surface features that indicate the presence of liquid water not far below. For example, scientists suggest that the ridges on Europa (yuh ROH puh), one of Jupiter’s moons, shown in Figure 4,could be cracks in the ice where liquid water has seeped to the surface and frozen solid. Callisto and Ganymede, two other moons of Jupiter, and Titan, a moon of Saturn, show similar surface features.

Several other moons in the outer solar system, including Enceladus (en SEL uh dus), a moon of Saturn, and Triton, a moon of Neptune, show evidence of geysers (GI zurz). Ageyseris a warm spring that sometimes ejects a jet of liquid water or water vapor into the air. The massive geysers on Enceladus shown in Figure 5are hundreds of kilometers high. Two other moons of Saturn, Tethys (TEE thus) and Dione (di OH nee), also have geyserlike plumes.

2.Key Concept CheckWhere might life exist in the solar system beyond Earth?